The United States has rejected the grounds of a lawsuit stemming from experiments involving sexually transmitted diseases and human subjects in Guatemala between 1946 and 1948.

At the same time, the government announced increased aid to Guatemala to fight STDs.

In its first response to the class-action lawsuit filed last March by the alleged victims and their heirs, the U.S. government argued that it is immune to such a lawsuit, in a motion to dismiss the suit filed Monday night.

Because the harm was suffered in a foreign country, and because the Guatemalans have not exhausted other administrative solutions, the United States has sovereign immunity under the Federal Tort Claims Act, it said in the motion.

The government said the Supreme Court has “clarified” that the immunity statute “bars all claims based on any injury suffered in a foreign country, regardless of where the tortuous act or omission occurred.”

The United States has apologized for the study, and President Barack Obama asked the Presidential Commission for the Study of Bioethical Issues to look into the details of the research and to assure him that current rules protect people from unethical treatment.

Meanwhile, on Tuesday, the U.S. Department of Health and Human Services announced it will invest about $1.8 million to aid the treatment and prevention of HIV and other sexually transmitted diseases in Guatemala.

The money will also “further strengthen ethical training on human research protections,” the agency said in a statement.

“These new activities are part of the Obama administration’s commitment to ensuring that the United States has the strongest possible human subject protections at home and around the world,” the statement said.

Likewise, the Centers for Disease Control and Prevention will increase funding to Guatemala by $775,000 over three years to help monitor and control the spread of STDs.

The controversy centers on the U.S. Public Health Service Sexually Transmitted Disease Inoculation Study of 1946-1948, which was conducted to determine the effectiveness of penicillin in treating or preventing syphilis after subjects were exposed to the disease. Gonorrhea and chancres were also studied. Penicillin was a relatively new drug at the time.

The tests were carried out on female commercial sex workers, prisoners in the national penitentiary, patients in the national mental hospital and soldiers. According to the study, more than 1,600 people were infected: 696 with syphilis, 772 with gonorrhea and 142 with chancres.

The lawsuit filed by the Guatemalan victims and their heirs compares the project to the Tuskegee syphilis experiment in Alabama. During that 40-year study that began in 1932, doctors observed how the disease progressed in about 400 poor African-Americans who already had syphilis. The men were never told they had the disease and were never treated for it. The test subjects received free medical testing, meals and burial insurance.

“This decision to move to Guatemala was part of a deliberate plan to continue the Tuskegee testing offshore, where it would not be subject to the same level of oversight as in the United States,” the lawsuit says.

In the experiments in Guatemala, consent was never given by the subjects, only by the institutions that housed them, the Guatemalans argue.